<template>
  <div class="s-canvas" @click="refreshCode">
    <canvas id="s-canvas" :width="contentWidth" :height="contentHeight" />
  </div>
</template>

<script setup lang="ts">
import { onMounted, ref } from 'vue'

const props = defineProps({
  //字体大小，最小值
  fontSizeMin: {
    type: Number,
    default: 16
  },
  //字体大小，最大值
  fontSizeMax: {
    type: Number,
    default: 40
  },
  //背景颜色色值最小值，最小为
  backgroundColorMin: {
    type: Number,
    default: 180
  },
  //背景颜色色值最大值，最大为255
  backgroundColorMax: {
    type: Number,
    default: 240
  },
  //画布（图片）宽度
  contentWidth: {
    type: Number,
    default: 112
  },
  //画布（图片）高度
  contentHeight: {
    type: Number,
    default: 38
  },
  //字体颜色色值最小值，最小为0
  colorMin: {
    type: Number,
    default: 50
  },
  //字体颜色色值最大值，最大为255
  colorMax: {
    type: Number,
    default: 160
  },
  //干扰线颜色色值最小值，最小为0
  lineColorMin: {
    type: Number,
    default: 40
  },
  //干扰线颜色色值最大值，最大为255
  lineColorMax: {
    type: Number,
    default: 180
  },
  //干扰点颜色色值最小值，最小为0
  dotColorMin: {
    type: Number,
    default: 0
  },
  //干扰点颜色色值最大值，最大为255
  dotColorMax: {
    type: Number,
    default: 255
  }
})
const emit = defineEmits(['identifyCode'])
// 生成验证码的字符范围
const identifyCodes = 'ABCDEFGHJKMNPQRSTWXYZabcdefhijkmnprstwxyz0123456789'
//展示的图片验证码
const identifyCode = ref('')

// 生成一个随机数
function randomNum(min: number, max: number) {
  return Math.floor(Math.random() * (max - min) + min)
}
// 生成一个随机的颜色
function randomColor(min: number, max: number) {
  let r = randomNum(min, max)
  let g = randomNum(min, max)
  let b = randomNum(min, max)
  return 'rgb(' + r + ',' + g + ',' + b + ')'
}
//利用canvas，生成图片验证码
function drawPic() {
  identifyCode.value = ''
  makeCode(4)
  let canvas = document.getElementById('s-canvas')
  let ctx = canvas?.getContext('2d')
  ctx.textBaseline = 'bottom'
  // 绘制背景
  ctx.fillStyle = randomColor(props.backgroundColorMin, props.backgroundColorMax)
  ctx.fillRect(0, 0, props.contentWidth, props.contentHeight)
  // 绘制文字
  for (let i = 0; i < identifyCode.value.length; i++) {
    drawText(ctx, identifyCode.value[i], i)
  }
  // drawLine(ctx),
  drawDot(ctx)
}
//画验证码
function drawText(ctx: any, txt: string, i: number) {
  ctx.fillStyle = randomColor(props.colorMin, props.colorMax)
  ctx.font = randomNum(props.fontSizeMin, props.fontSizeMax) + 'px SimHei'
  let x = (i + 1) * (props.contentWidth / (identifyCode.value.length + 1))
  let y = randomNum(props.fontSizeMax, props.contentHeight - 5)
  var deg = randomNum(-45, 45)
  // 修改坐标原点和旋转角度
  ctx.translate(x, y)
  ctx.rotate((deg * Math.PI) / 180)
  ctx.fillText(txt, 0, 0)
  // 恢复坐标原点和旋转角度
  ctx.rotate((-deg * Math.PI) / 180)
  ctx.translate(-x, -y)
}
// 干扰线
function drawLine(ctx: any) {
  // 绘制干扰线
  for (let i = 0; i < 8; i++) {
    ctx.strokeStyle = randomColor(props.lineColorMin, props.lineColorMax)
    ctx.beginPath()
    ctx.moveTo(randomNum(0, props.contentWidth), randomNum(0, props.contentHeight))
    ctx.lineTo(randomNum(0, props.contentWidth), randomNum(0, props.contentHeight))
    ctx.stroke()
  }
}
// 干扰点
function drawDot(ctx: any) {
  // 绘制干扰点
  for (let i = 0; i < 100; i++) {
    ctx.fillStyle = randomColor(0, 255)
    ctx.beginPath()
    ctx.arc(randomNum(0, props.contentWidth), randomNum(0, props.contentHeight), 1, 0, 2 * Math.PI)
    ctx.fill()
  }
}
// 生成随机验证码
function makeCode(l: number) {
  for (let i = 0; i < l; i++) {
    identifyCode.value += identifyCodes[randomNum(0, identifyCodes.length)]
  }
  // console.log(identifyCode.value)
}

function refreshCode() {
  drawPic()
  emit('identifyCode', identifyCode.value)
}

onMounted(() => {
  drawPic()
  refreshCode()
})
</script>

<style lang="less" scoped>
.s-canvas {
  width: v-bind(contentWidth) + 'px';
  height: v-bind(contentHeight) + 'px';
}
</style>
